I was under the impression that his quote from JonCon isn't about getting the greyscale, but it's his thoughts about the situation now that he has it. He doesn't want to wait and hide Aegon anymore, and doesn't have time to be cautios _because_ he now has greyscale. If he hadn't gotten the illness, then he might have been more careful with how they go forth with their plan of conquering Westeros, but now that he knows he's going to be a petrified Griffin soon, it doesn't really matter.